The Voice: Fights, fallouts and the end of the show forever!

With dark circles under their eyes and ashen faces, they looked drastically different from their glamorous onscreen personas as they jetted out of Sydney last week.

And it's little wonder the normally smiling The Voice coaches were keeping their heads down.

Insiders say what was meant to be a post-finale celebration ended in fights and chaos when coaches Delta Goodrem and Kelly Rowland got into a row at the show's wrap party.

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"Tension had been brewing between them for weeks but it came to a head at the party when Delta accused Kelly of trying to bulldoze her," an insider dishes to Woman's Day.

"Kelly then accused Delta of trying to push her off the show, saying Delta always wanted to be the star and used the fact Kelly was American to alienate her off-set and make her feel like she didn't fit in.

"They had a row, and Kelly broke down in tears after Delta said she was sick of Kelly trying to undermine her and patronise her at every opportunity," our insider adds. "Afterwards, Kelly was heard swearing she won't be back for the next season."

Oh it's on, Kelly.

The pressures of long hours and rumours about the show's future and which judges will be back, combined with the low grand finale ratings, led to the blow-up, reveals our source.

And it didn't help when Joe Jonas seemed to side with Kelly, saying Delta used "her 'Aussie pride' thing against the others".

"Everyone knows Boy George can be a bit of a diva and a sore loser. It would've really pissed him off that Sam was crowned winner," tells another source.

The hammering George took on social media for his duet of the Eurythmics' Sweet Dreams with finalist Sheldon, also would have really hit a nerve.

WATCH: Boy George and Sheldon Riley's polarising performance on the grand finale of The Voice.

"Omg... Boy George can't sing!'' wrote one fan.

Another said his performance was so bad it was killing the show:

"@BoyGeorge and @SheldRiley sound as bad as each other. If this is what we are putting through to #TheVoiceAU then i think it's time is up. Ditch the show!"

Now, with speculation mounting that Boy George is angling to jump ship to the US franchise, and with Kelly already threatening to quit, insiders say Nine bosses have called a "crisis meeting" to discuss the future of the singing contest.

"With two of the show's major talents threatening to walk away, the executives are scrambling around to try and keep Delta and Joe happy," a Nine insider explains.

"But there's also the very real possibility that it might be time to pull the pin on the show entirely."